Watercraft sports which involve a person propelling a watercraft through a body of water, such as a river or lake, are popular outdoor activities. A watercraft sport which is of particular interest in the present application is kayaking. Although kayaks may be of many designs, a kayak will almost always include a hull which is pointed at both ends and which is covered with a full deck except for a centrally located cockpit.
The cockpit is specifically designed to accommodate a paddler in a certain sitting position. To this end, the cockpit usually includes a shallow seat and a foot brace. The shallow seat is attached to the bottom surface of the kayak in a location to the rear of the cockpit. The foot brace is attached to the bottom surface of the kayak at a location in front of the cockpit, and thus beneath the deck of the kayak. To begin a kayaking session the paddler sits on the shallow seat and separates and slightly bends his/her knees so that they create a V-shape form relative to the bottom surface of the kayak. The paddler's feet are placed on the foot brace and the top portion of his/her thighs are abutted against the underside of the deck in front of the cockpit.
In the actual kayaking process, the paddler will manipulate a single kayak paddle to propel the kayak through the water. A kayak paddle includes a paddle-shaft with two blades attached to opposite ends thereof. In this manner, one blade may be positioned on each side of the kayak. Although some rather sophisticated blade designs may be incorporated into a kayak paddle, the geometry of most, if not all, kayak blades will roughly approximate a planar surface.
While the kayaking stroke is quite complex, it may be initially viewed as alternately moving the blades of the paddle through the water. After a paddler is properly positioned in a kayak, the paddle-shaft is grasped in such a manner that the paddler's hands are in the same vertical plane as his/her respective shoulder. Consequently, the location of a paddler's hands on a paddle-shaft will depend on his/her physical make-up. More particularly, persons of different sizes will grasp a paddle-shaft in different locations and kayak paddles are therefore, usually designed to accommodate this "variable-grasp" phenomenon.
A kayaking stroke may be viewed as a combination of complimentary movements of each blade. These movements specifically include, for each blade, a air-push step, a water-entry step, a water-pull step and a water-exit step. Because the steps of the kayaking stroke are complimentary, not simultaneous, for the respective blades, one blade will be in a certain step while the other blade is a complimentary step of the kayaking stroke. More particularly, while one blade is in the air-push step, the other blade will be in the water-pull step thereby complimenting the pull with a push. Additionally, while one blade is in the water-entry step, the other blade will be in the water-exit step. Thus, the kayaking stroke may be viewed as four "combination" stages, namely a air-push/water-pull stage, a water-entry/water-exit stage, a water-pull/air-push stage, and a water-exit/water-entry stage.
Although the steps of the kayaking stroke are explained more fully below, it may be noted at this point that during the water-pull step the relevant blade will travel in water and that during the air-push stage the relevant blade will travel in air. When a blade is traveling through the water during the water-pull step, it is desirable to catch as much water resistance as possible to ensure efficient propelling. Conversely, because overcoming air resistance does little to propel the kayak, it is desirable to have as little air resistance as possible during the air-push step.
For these reasons the planar orientation of the blades will commonly be offset approximately 90.degree. relative to each other. In this manner, one blade may travel through the air in a substantially horizontal plane to minimize air resistance, while the other blade may travel through the water in a substantially vertical plane to maximize propelling efficiency. However, as is explained in more detail below, this desirable design factor requires appropriate manipulations, or "paddle-shaft twisting", during the kayaking stroke to insure that the blade is properly positioned during the air-push and water-pull steps.
The details of the kayaking stroke are best explained by reviewing each of the four "combination stages" of the stroke. At what may be termed a starting point, the right blade is positioned to begin the air-push motion and the left blade is positioned to begin the water-pull motion. More particularly, the right hand, and the portion of the paddle-shaft gripped therein, are positioned at approximately ear level with the right elbow pointing down and slightly away from the body. The left arm is fully extended and positioned below the right arm and the left blade is positioned in the water, preferably as close to the side of the kayak as possible. Additionally, the right blade is positioned in a substantially horizontal plane to reduce air resistance during the subsequent air-push stage. This results in the left blade being positioned in a substantially vertical plane maximize efficiency during the subsequent water-pull stage.
To begin the air-push/water-pull stage, the right blade is pushed forward and the left blade is pulled rearward. The forward pushing of the right blade is accomplished by an inward and forward extension of the right arm and the rearward pulling of the left blade is accomplished by a retraction of the left arm. More specifically, the right arm is extended forward by rotation of the shoulders, torso and abdomen, and at the end of this air-push stroke, the right hand should be positioned over the kayak's axial centerline. One may appreciate that, because the right blade is traveling through the air, a minimum amount of energy is required to execute this forward pushing.
Regarding the rearward pulling of the left blade, this movement is accomplished by pulling with the lower arm in manner that the paddle-shaft remains perpendicular to the wrist and the lower forearm is parallel to the water surface. The paddle-shaft should remain fairly vertical throughout this water-pull step and the left blade should be kept as close to the kayak as possible to minimize any turning of the boat. If the water-pull stage is correctly performed, the majority of the "pulling" power will come from the twisting/untwisting of the paddler's torso.
The end of the air-push/water pull stage of the kayaking stroke marks the beginning of the water-entry/water-exit stage. In this stage, the right blade is implanted in the water and the left blade is removed from the water. However, slightly before this implantation and removal, the paddle-shaft is twisted so that the right blade is positioned in a substantially vertical plane and the left blade is positioned in substantially horizontal plane.
The water-entry of a kayak blade is critical for maximum power and efficiency because it places the blade in the vertical orientation necessary for the effective application of power. A properly executed water-entry gives the blade a "firm grip" on the water so that the kayak moves forward in relation to the blade, or in other words, moves the kayak towards the blade. Some commentators suggest that a paddler should visualize setting the blade in concrete so that the kayak, not the blade, moves through the water. In any event, at the completion of this water-entry step, the right blade is ready to begin the water-pull stage of the kayaking stroke.
The water-exit stage is performed by withdrawing the left blade from the water when the left hand becomes even with the paddler's hip. This withdrawal is accomplished by moving the left hand upward and continuing this upward movement until the left hand is positioned approximately at ear level with the left hand pointing down and slightly away from the body. It may be noted for future reference that this positioning places the paddler in a condition to begin a subsequent air-push stage.
Timing is especially crucial in the water-exit stage because if the blade exits the water too early, a paddler is essentially cheated of potential "pulling" power. Conversely, if the blade exits the water too late, the blade drags thereby frustrating the forward progress of the kayak. Additionally, a "late" water-exit will require a backwards pull on the paddle to get the blade out of the water. This backwards pull is a nonproductive use of energy and moreover, may cause the back of the kayak to sink slightly, thereby further impeding the forward travel of the kayak.
After completion of this water-entry/water-exit stage of the kayaking stroke, the paddler is positioned to begin the water-pull/air-push stage. More specifically, the right paddle is positioned to begin the water-pull step and the left paddle is positioned to begin the air-push step. Thus, these steps may be performed in the above-described manner.
One may appreciate that the kayaking stroke requires a pivoting of the center of the kayak-paddle to accomplish the complementary stages of the stroke. However, it is important to note that this pivoting does not occur about a fixed pivot point. Instead, the "pivot point" of the kayaking stroke travels in a three-dimensional path during the various stages of the stroke, and thus, may be more accurately termed a "pivot space." Additionally, the size, shape, and location of this pivot space will vary for different paddlers.
Due to the unique nature of the kayaking stroke, it requires a paddler to learn a certain technique of paddling which differs greatly from those used in other water craft sports, such as rowing and canoeing. Additionally, the particular muscle development required for enhanced or competitive kayaking is believed to be distinctive for this particular watercraft sport. More particularly, the kayaking stroke exercises the wrist flexors, wrist extensors, biceps, and triceps in a paddler's arms. Additionally, certain muscle groups in the paddler's torso are also exercised, such as the deltoids, pectoralis major, trapezius, latissimus dorsi, spinal rotators, rhomboids, rotator cuffs, and the abdominals. Still further, the kayaking stroke requires isometric resistance for the lower extremity of the paddler's body.
Consequently, for economic and time-constraint reasons, a paddler may wish to develop his/her kayaking skills without actually putting a kayak in the water. In the past, exercise machines have been developed to simulate certain outdoor activities such as bicycling, cross-country skiing, and perhaps most relevant in this discussion, rowing. However due to the uniqueness of the kayaking stroke, these machines are believed to be unsuitable for indoor kayak training. More specifically, these machines do not allow for simulation of "paddle-twisting" and sometimes do not permit variable hand positions. Additionally, to the extent that conventional machines allow for rotation of some sort of shaft, the rotation usually must occur around some fixed pivot point, rather than a three-dimensional pivot space. Still further, these machines usually do not compensate for the change in resistance in the air-push and water-pull stages of the kayaking stroke nor do they imitate the blade-specific resistance during the water-pull stage.
Applicants therefore believe that a need remains for a kayak simulator machine which accurately simulates the kayaking motion and thereby develops the correct kayaking technique as well as exercising the appropriate muscles.